WASHINGTON, April 2 (Reuters) - Cities that quickly closed schools and discouraged public gatherings had fewer deaths from the great flu pandemic in 1918 than cities that did not, researchers reported on Monday.
Decisive, immediate action can reduce the most acute effects of a pandemic, while allowing the population to build some natural immunity to the virus, the U.S. government study found.
Experts agree that a pandemic of some virus, most likely influenza, is almost 100 percent certain. What is not certain is when it will strike and which virus it will be.
The worst-case scenario is the 1918 flu pandemic, which killed tens of millions of people globally. Researchers are going through records to learn from the actions taken decades ago.
Dr. Richard Hatchett of the National Institute of Allergy and Infectious Diseases and colleagues studied 17 U.S. cities.
"Cities in which multiple interventions were implemented at an early phase of the epidemic had peak death rates about 50 percent lower than those that did not," they wrote in their report, published in the Proceedings of the National Academy of Sciences.
In Kansas City, no more than 20 people could attend weddings or funerals. New York mandated staggered shifts at factories. In Seattle, the mayor told people to wear face masks.
No single action worked on its own, the researchers found, it was the combination of measures that saved lives.
The World Health Organization has been urging countries to get ready for a pandemic. The H5N1 avian influenza is considered the most likely candidate to cause one.
So far, it has spread mostly in birds, across Asia and into Africa and Europe. But it sometimes infects people and has killed 170 people out of 288 known to have been infected.
LESSONS FROM PAST
It is constantly evolving and if it mutates in just the right way, it could spread easily from one person to another, causing widespread death and sickness.
No good vaccine would be available for months, and drugs that treat influenza are in very short supply.
So experts are looking at what they call non-pharmacologic interventions — ways to prevent infection without drugs. They hope this can buy time while companies make and distribute vaccines and drugs.
Because the virus is spread by small droplets passed within about three feet (1 metre) from person to person, keeping people apart is considered a possible strategy.
Hatchett’s study suggests this worked nearly a century ago.
"The first cases of disease among civilians in Philadelphia were reported on Sept. 17, 1918, but authorities downplayed their significance and allowed large public gatherings, notably a citywide parade on Sept. 28, 1918, to continue," they wrote.
"School closure, bans on public gatherings, and other social distancing interventions were not implemented until Oct. 3, when disease spread had already begun to overwhelm local medical and public health resources," they added.
St. Louis authorities introduced "a broad series of measures designed to promote social distancing" as soon as flu showed up.
Philadelphia ended up with a peak death rate of 257 people per 100,000 population per week. St. Louis had just 31 per 100,000 at the peak.
When the cities relaxed their policies, death rates rose.
The U.S. government flu plan calls for similar measures, including allowing employees to stay home for weeks or even months, telecommuting and closing schools and perhaps large office buildings.